3,951 research outputs found
Integration of finite element modeling with solid modeling through a dynamic interface
Finite element modeling is dominated by geometric modeling type operations. Therefore, an effective interface to geometric modeling requires access to both the model and the modeling functionality used to create it. The use of a dynamic interface that addresses these needs through the use of boundary data structures and geometric operators is discussed
Inference for Adaptive Time Series Models: Stochastic Volatility and Conditionally Gaussian State Space Form
In this paper we replace the Gaussian errors in the standard Gaussian, linear state space model with stochastic volatility processes. This is called a GSSF-SV model. We show that conventional MCMC algoritms for this type of model are ineffective, but that this problem can be removed by reparameterising the model. We illustrate our results on an example from financial economics and one from the nonparametric regression literature. We also develop an effective particle filter for this model which is useful to assess the fit of the model.Markov chain Monte Carlo, particle filter, cubic spline, state space form, stochastic volatility.
Integration of geometric modeling and advanced finite element preprocessing
The structure to a geometry based finite element preprocessing system is presented. The key features of the system are the use of geometric operators to support all geometric calculations required for analysis model generation, and the use of a hierarchic boundary based data structure for the major data sets within the system. The approach presented can support the finite element modeling procedures used today as well as the fully automated procedures under development
Gravity gradient boom stabilization system for the Applications Technology Satellite /ATS-E/, volume 1 Final report
Gravity gradient boom stabilization system for ATS
Financial work incentives in Britain: comparisons over time and between family types
This paper reviews various techniques for quantifying financial incentives to work, shows how financial work incentives have changed across the population since 1979, and estimates how much of these changes are due to changes in the tax and benefit system
Anisotropic Boundary Layer Adaptivity of Multi-Element Wings
Multi-element wings are popular in the aerospace community due to their high
lift performance. Turbulent flow simulations of these configurations require
very fine mesh spacings especially near the walls, thereby making use of a
boundary layer mesh necessary. However, it is difficult to accurately determine
the required mesh resolution a priori to the simulations. In this paper we use
an anisotropic adaptive meshing approach including adaptive control of elements
in the boundary layers and study its effectiveness for two multi-element wing
configurations. The results are compared with experimental data as well as
nested refinements to show the efficiency of adaptivity driven by error
indicators, where superior resolution in wakes and near the tip region through
adaptivity are highlighted.Comment: 52nd Aerospace Sciences Meetin
Using Adobe Flash Lite on mobile phones for psychological research: reaction time measurement reliability and inter-device variability
Mobile telephones have significant potential for use in psychological research, possessing unique characteristics—not least their ubiquity—that may make them useful tools for psychologists. We examined whether it is possible to measure reaction times (RTs) accurately using Adobe Flash Lite on mobile phones. We ran simple and choice RT experiments on two widely available mobile phones, a Nokia 6110 Navigator and a Sony Ericsson W810i, using a wireless application protocol (WAP) connection to access the Internet from the devices. RTs were compared within subjects with those obtained using a Linux-based millisecond-accurate measurement system. Results show that measured RTs were significantly longer on mobile devices, and that overall RTs and distribution of RTs varied across device
A highly sensitive liquid chromatography electrospray ionization mass spectrometry method for quantification of TMA, TMAO and creatinine in mouse urine
Our method describes the quantification in mouse urine of trimethylamine (TMA), trimethylamine N-oxide (TMAO) and creatinine. The method combines derivatization of TMA, with ethyl bromoacetate, and LC chromatographic separation on an ACE C18 column. The effluent was continuously electrosprayed into the linear ion trap mass spectrometer (LTQ), which operated in selective ion monitoring (SIM) modes set for targeted analytes and their internal standards (IS). All validation parameters were within acceptable ranges of analytical method validation guidelines. Intra- and inter-day assay precision and accuracy coefficients of variation were <3.1%, and recoveries for TMA and TMAO were 97–104%. The method developed uses a two-step procedure. Firstly, TMA and TMAO are analyzed without a purification step using a 5-min gradient cap-LC- SIMs analysis, then creatinine is analyzed using the same experimental conditions. The method is robust, highly sensitive, reproducible and has the high-throughput capability of detecting TMA, TMAO and creatinine at on-column concentrations as low as 28 pg/mL, 115 pg/mL and 1 ng/mL, respectively. The method is suitable for analysis of TMA, TMAO and creatinine in both male and female mouse urine. / The key benefits of the method are: The small sample volume of urine required, which overcomes the difficulties of collecting sufficient volumes of urine at defined times. / No sample pre-treatment is necessary. / The quantification of TMA, TMAO and creatinine using the same cap-LC-MS method
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